Broaching machine



Nov., M, i950 B. wELTE 2,529,718

BROACHING MACHINE Filed Aug. 2l, 1944 2 Sheets-Shea?l 2 I wle auf I 40 I/gg 2&5' vane/,z l

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Patented Nov. 14, 1950 ,sais

BROACHING MACHINE Benedict Welte, Lake Orion Township, Oakland County,Mich., assigner to Colonial Broach Company, Delaware Detroit, Mich., acorporation of Application August 21, 1944, Serial No. 550,330

Claims.

The present invention relates to an automaticcontrol mechanism foroperating a plurality of positive displacement hydraulic motors in ahydraulically-operated machine through a complete cycle of operations.

One object of the present invention is to provide an improved andsimplified type automaticcontrol mechanism for operating a plurality ofhydraulic piston and cylinder units through a desired cycle ofoperations, which mechanism is readily adaptable to various types ofmachines.

Another object of the present invention is to provide anautomatic-control mechanism of the type mentioned, in which safetyinterlocks are provided to prevent normal operation of any motor whereanother of the motors is in an improper position and which willautomatically restore the improperly positioned motor or motors to theirproper positions and then cause a resumption of the normal cycle ofoperations.

Another object of the present invention is to provide anautomatic-control mechanism of the type mentioned having a simple,manuallyoperated means for selectively shifting each motor in eitherdirection to facilitate machine set-up operations.

Another object of the present invention is to provide anautomatic-control mechanism of the type mentioned which is peculiarlyadapted for use with an independent source of operating liquid for eachmotor, such as is provided when use is made of the multiple flow-controlvalve mechanism of applicants copending application, Serial No. 548,294,filed August 5, 1944.

A further object of the invention is to provide a control mechanism ofthe type described which incorporates means for independently adjustingthe speed of operation of each of the motors.

Another object of the invention is to provide an automatic-controlmechanism of the type mentioned, in which an improved and simplifiedelectrical circuit is employed to control the operation of the mainvalves of the hydraulic system with resulting simplication of theinterlocking mechanism.

Another object of the invention is to provide an automatic-controlmechanism having the above mentioned advantages for cycling the cylinderand piston units of a shuttle-type pull broaching machine having a workmoving cylinder which is simple in construction and positive andfool-proof in operation.

Other objects and advantages will become apparent from the followingspecification, the accompanying drawings, and the appended claims.

Referring to the drawing in which like numerals are applied to likeparts in the several Views, Figure 1 is a diagrammatic illustration ofthe mechanical and hydraulic portions of a shuttle-type pull broachingmachine having a moving table and incorporating a portion of the controlmeans of the present invention.

Figure 2 is a fragmentary side elevation of a portion of one of themechanically operated electric switches illustrated in Figure 1.

Figure 3 is a diagrammatic illustration of the electrical circuitemployed to control the operation of the mechanism illustrated in Figure1.

While the invention is applicable to various types of hydraulicallyoperated machines the particular embodiment illustrated is speciallydesigned and arranged to control the operation of the shuttle-typepull-down broaching machine having a work moving table or iixture whichmoves the workpiece into and out of broaching position. Such machinesincorporate at least three positive displacement piston and cylinderunits or motors. One of these units operates what is generally referredto as the broach-handling chuck; the second operates the breach-pullingchuck, and the third operates the table or fixture which moves theworkpiece into and out of breaching position. These piston and cylinderunits may either be of the type embodying a stationary cylinder and amovable piston or of the type embodying a stationary piston and amovable cylinder. The particular mechanism illustrated in Figure 1 is ofthe latter type, in which the pistons are stationary and mechanicalfeatures of the machine in general may be of the type illustrated ingreater detail in'applicants copending application, Serial No. 495,856,led July 23, 1943, and now Patent No. 2,395,702, granted Feb. 26, 1946.In this connection it may be noted that the broach-handling and pullingchucks are preferably of the conventional type which contain means topositively lock the broach in the chuck and which have a release sleevewhich engages a fixed abutment at the end of the inward stroke of thechuck and is thereby shifted axially to release the broach. A chuck ofthis type is shown in Fig. 3A of Hart Patent 2,162,814.

Referring to Figure 1 there is illustrated a movable breach-pullingcylinder I to which is secured in any desired manner, not illustrated,the broach-pulling chuck, a movable breachhandling cylinder 2, to whichis secured in any desired manner the broach handling chuck and a movableworktable operating cylinder 3. Cylinder I contains a piston 4 which issecured by means of a hollow piston rod to a stationary manifold 6. Theinterior of the hollow piston rod 5 communicates through the manifold inthe manner indicated by the dotted line 1 with a pipe 8. The hollowpiston rod 5 and the manifold provide means for conducting liquid underpressure to the lower end of the cylinder I. Likewise, xed to themanifold 8 is a second pipe 9 which projects into the cylindei1 i andprovides means for conducting liquid under pressure to the upper end ofthe cylinder I. Pipe 9 communicates through the manifold, as indicatedby the dotted line I8, with a pipe II, which contains a conventionalfoot valve I2. The foot valve I2 serves to offer sufficient resistanceto now of liquid from the upper end of the cylinder I through the pipe II to prevent cylinder I from moving down under the influence of gravity.The foot valve offers no appreciable resistance to now in the oppositedirection. The valve may he of any desired construction, such as thatindicated generally by the numeral 324 in Figure 9 of applicantsaforementioned copending application, Serial No. 495,856, now Patent No.2,395,702.

While, for purposes of illustration, the pipe 9 and piston rod 5 areshown as separate pipes leading to opposite ends of the movable cylinderI, it is preferred, in the actual construction, that these two pipes beconcentrically arranged in the manner shown in Hart Patent No.2,190,667.

The handling cylinder 2 is similarly provided with a stationary pistonI3 having a hollow piston rod I4 connected to a stationary manifold I5.The hollow piston rod I4 provides a path for uid communication to theupper end of the handling cylinder 2. A second pipe I6, also connectedto the manifold I5, supplies uid to the lower end of cylinder 2, thearrangement of the pipes I4 and I8 being similar to that referred toabove in connection with pipes 5 and 9 in cylinder I. Pipe I4communicates through the manifold with a pipe I1 which contains a footvalve I8 similar to the foot valve I2, previously mentioned. Pipe I6communicates through the manifold with a pipe I9. The work handlingcylinder 3 is likewise provided with a stationary piston 2li having ahollow piston rod 2l which is xed to a stationary manifold 22 andsupplies iiuid to the lefthand end of the cylinder 3. The cylinder alsohas a stationary pipe 23 xed to the manifold 22 which supplies fluid tothe righthand end of the cylinder. Piston rod 2| communicates with pipe24, and pipe 23 communicates through the manifold with the pipe 25.

It will be apparent from the above that the six pipes 8, II, I1, I9, 24,and 25 serve to conduct the operating fluid to and from the threemotors, each pipe being effective when it conducts pressure fluid toeffect a movement of one of the cylinders in one direction. The presentinvention requires that each of these pipes be provided with a valvewhich is effective in one position to conduct liquid under pressure tothe pipe, and in the other position to connect the pipe. to aAlow-pressure reservoir. In order to realize the full advantage of theimproved control and mechanism, which constitutes one feature of thepresent invention, it is essential that these valves be provided withvalve-shifting means incorporating a solenoid which, when energized,effects a shift of the valve in one direction in combination withsuitable means to return the valve when the solenoid is not energized.The six lines illustrated may, if desired, be provided with individualvalves of this type, but in the embodiment of the invention illustratedeach pair of pipes is connected to a four-way valve having a singlesource of liquid under pressure, and a single pipe line leading to thelow-pressure reservoir. Such four-way valves are in effect twoindividual three-way valves combined in a single valve.

The particular four-way valves employed in the preferred embodiment ofthe invention illustrated are conventional four-way valves of the typehaving an axially shiftable spool, a pair of solenoids each effectivewhen energized to shift the spool in one of its two directions ofmovement, respectively, and a spring-centering device which is effectivewhen neither solenoid is energized to shift the spool to a centralposition in which it blocks all flow through the valve. The solenoidsmay either act directly on the valve spool or control a pilot valvewhich supplies hydraulic pressure to shift the valve spool. Since suchValves are old and 'well known, they are merely vindicated.diagrammatically in the drawings. As hereinafter pointed out, the springcentering device may be omitted from valve 38, if desired, in whichevent the valve is preferably provided with any conventional form ofspring-pressed detent which will hold the valve spool againstdisplacement from either of its two positions of adjustment when neithersolenoid is energized.

Pipe lines 8 and II for the main cylinder I are connected to aspring-centered blocking center four-way valve 26 having a pair ofsolenoids 21 and 28. The construction is such that when the solenoid 28is energized the spool of the valve shifts to its lefthand position, inwhich it connects pipe II to the pressure supply line 2-6 andsimultaneously connects pipe 8 to a pipe 3 I, which is in communicationwith the low-pressure reservoir 32. When solenoid 21 is energized thespool of the valve shifts to its right-hand position, in which pipe IIis connected to the low-pressure pipe 3l and pipe 8 is connected to thepressuresupply line 38. When neither solenoid is energized all flowthrough the valve is blocked.

The pair of pipes I1 and I9 for the broachhandling cylinder 2 isprovided with a similar four-way valve 33 having a pair of operatingsolenoids 34 and 35, a pressure supply line 36 and a pipe 31, which isin fluid communication, not shown, with the low-pressure reservoir.Likewise the pair of pipes 24 and 25 are provided with a similarfour-way valve 38 having a pair of operating solenoids 39 and 48, apressure-supply line 4I, and a low-pressure reservoir return line 42.

While in a broad sense the pressure-supply lines 3U, 36, and 4I mayreceive a suitable supply of pressure iiuid from any desired source, inaccordance with one aspect of the invention these lines receive fluidfrom a multiple flow-control valve mechanism which may be any one of thevarious forms of such mechanism disclosed in applicants copendingapplication, Serial No. 548,294, filed August 5, 1944.

The particular form of multiple flow-control mechanism illustratedincludes a valve housing 43 provided with an internal cylindricalchamber 44 in which is slidable a piston 45 carrying a valve plunger 46which controls a discharge port 41 in the housing. The chamber 44 isprovided with an inlet port 48 connected by pipe 49 to a positiveconstant-displacement pump 50, the intake line 5| of which is connectedto the low-p-ressure reservoir 32. A spring 52 acts on the piston 45 toforce it in a direction to cause the plunger 46 to close the outlet port41, which outlet is connected to the low pressure reservoir 32 by a pipe53. The tapered end of the plunger 46 is preferably tapered at aslightly steeper angle than the tapered seat at port 41 in accordancewith common practice so that the eiTective seating area is equal to thefull cross-sectional area of plunger 46. The piston 45 has an upwardlyprojecting cylindrical plunger 54 which fits a reduced cylindricalchamber portion 55. The entire valve element including the piston 45 andthe plungers 46 and 54, is provided with an axial opening indicated indotted lines at 56, which opening extends entirely through the element.

The valve housing is provided with an outlet port 51 which is incommunication with the inlet port 48 at all times, regardless of theposition of the plunger 46. The outlet 51 is connected to a pipe 58, inwhich is positioned an adjustable throttle valve 59. The valve 59constitutes a restriction in the line 58, which restriction can beadjusted by manipulation of the handle 6D. The degree of restrictionprovided by the valve 59 is preferably that required to cause arelatively small pressure drop in line 58 when the quantity of liquidpassing through the valve is that required to operate the main cylinderat its desired speed. For example, in a system having a maximumoperating pressure of 1000 pounds per square inch, the valve 59, whenfully opened, may cause a pressure drop of approximately twenty poundsper square inch during passage of the full discharge of pump- 58. Byadjusting the valve 59 to increase its restricted effect, the amount ofiiow for the given pressure drop may be reduced.

The spring 52 is of such stiffness that it will just balance a pressuredifferential on opposite sides of the piston 45 equal to the pressuredrop through valve 59, when the desired amount of liquid is owingthrough the latter valve. Thus, in the example given., the spring 52would balance a pressure differential on opposite sides of the piston45, of twenty pounds per square inch. The design and construction of thespring should be such that no material increase in pressure is exertedby it when the valve plunger 46 moves from fully closed to fully openposition..

Pipe 58 is connected directly to the pipe 38 which supplies the pressurefluid to the main four-way valve 26, and it is also directly connectedto a pipe 6| which in turn is connected to previously described pipes 36and 4| through adjustable throttle valves 62 and 63 located,respectively, in the pipes 36 and 4|. The adjustable throttle valves 62and 63 are identical in construction to the valve 59 except that in theparticular embodiment of the invention they are of smaller size, beingso designed as to produce the same pressure drop as the valve 59 but forthe smaller quantity of liquid required to operate the smaller cylinders2 and 3 at the desired speeds.

The space within the chamber 44 above the piston 45 is connected bymeans of -a port 64 and a line 65 to a low-pass valve 66, having aninternal chamber 61 provided with a pair of axially spaced internalannular grooves 68 and 69 which are connected by means of a passageway10 to each other and to the line 65. The chamber 61 contains a movableplunger or spool 1| having a pair of annular channels 12 and 13. Theannular channel 12 is connected by cross passageway 14 and an axialpassageway 15 to the lefthand end of the spool, while the channel 13 isconnected by a cross passageway 16 and an axial passageway 11 to therighthand end of the spool. The spool is so constructed that when it isin the lefthand position illustrated, channels 12 and 68 are incommunication with each other and the spool blocks channel 69. When thespool is in the righthand position, channels 13 and 69 are incommunication with each other and the spool blocks channel 68. The endsof the valve housing 66 are connected by means of a pair of pipes 18 and19, respectively, to the pipes 36 and 4| at points in the latter locatedbeyond the adjustable throttle valves 62 and 63, respectively. As 4aresult of this arrangement, the upper end of chamber 44 and pipe 65 arein fluid communication with and subject to the pressure in that one ofthe two pipes 18 and 19 which is at the lowest pressure. Thus, when thepressure in line 18 is less than the pressure in line 19, the spool 1|will be forced to the left into the position shown in which it connectspipes 65 and 18. When pipe 19 is subject to a lower pressure than pipe18, the spool will shift to the right and connect lines 65 and 19. Asshown in the drawing, the end closure plates 66a and 66h of the housing66 are recessed and each recess is provided with an inwardly projectinglug 66e and 66d, respectively, for limiting endwise movement of thespool 1l.

l The lugs are of limited radial and circumferential extent in orderthat substantially the entire end areas of the spool will be subject tothe pressure from lines 18 and 19. If desired, a spring may be providedfor normally holding the spool 1| in its lefthand position illustratedwhen the pressures in the lines 18 and 19 are equal. The spring 88preferably exerts suilicient force on the spool 1| to overcome apressure differential between the lines 18 and 19 equal to approximatelyhalf of the pressure differential Awhich would be balanced by the spring52 of valve 43.

Valve chamber 43 contains a countersunk passageway 8| in communicationwith the port 64. The passageway 8| contains a spring-pressed ball checkvalve 82 which normally closes communication between the passageway 8|and a line 83 which is connected to the low-pressure reservoir 32 in anydesired manner, not illustrated. The spring 84 of the ball check valveis of such stiiT- ness as to permit opening of the check valve 8| onlywhen the pressure in line 65 exceeds the safe operating pressure for thesystem. The check valve thus limits the pressure which can act on theupper side of piston 45 to a safe maximum with the result that the valveplunger 46 will move upwardly and discharge oil from the pump 50 to thereservoir through line 53 when the pressure below the piston 45 exceedsthat maximum plus the small additional pressure necessary to overcomespring 52. The existence of a pressure drop necessary to overcome spring52 is insured by the bleed restriction 85 provided in the line 65. Thismechanism, therefore, provides a safety over-pressure relief for thesystem.

The space within the chamber 44 above piston 45 is also connected bymeans of a port 86 and 4a line 8l to a blocking valve 8S which isoperated by means of a solenoid 33. The blocking valve 88 may be of anydesired or conventional construction, it being sufcient only that itblock now through line 8l except when the solenoid 89 is energized. Thevalve 88, when opened, permits unrestricted ow through the line 81 to aline 90 which is connected to the low pressure reservoir. Consequently,the valve 88 serves as means for venting the space above the piston 45and thereby entirely relieving the pressure on the system when desired.

The mechanism so far described operates in th following manner. If it beassumed that the pump 59 is running and that none of the solenoids 2l,28, 34, 35, 39, or 40 is energized, the lines 35, 36, and 4l will beblocked by the blocking four-way valves 25, 33, and 38, and there willbe no outlet for the uid delivered to the valve housing 43 exceptthrough the outlet port 4l. The pressure in line i3 will be transmittedwithout change through the valve 43 and through lines 58, El, 36, 18,the low-pass valve G5, line 55, and port G4 to the upper end of thevalve chamber 44. There being no outlet for the uid delivered, thepressure will immediately build up to open the ball check valve 82, thusventing the uid in the valve chamber above piston 65 and causing thevalve plunger 46 to open fully and discharge all of the fluid deliveredby the pump to the reservoir through the line 53 at the maximum safeoperating pressure of the system. Under these circumstances the pressuredrop through the bleed restriction 85 will be sufficient to overcome theaction of spring 52 and, consequently1 the pump discharge pressure willexceed the pressure in the ball check valve line SI by the relativelysmall pressure drop required to overcome spring 52. f it is desired torelieve the pressure upon the pump this may be done by energizingsolenoid 89 and thus opening valve 88. This mediately connects the upperend of chamber @Il directly to the low-pressure reservoir and,consequently, the pressure above the piston 45 will be substantiallyzero. Under these circumstances the valve plunger 4'! Will open fullyand discharge all the iluid delivered by the pump to the reservoirthrough line 53 at the relatively low pressure required to overcomespring 52. Under these circumstances the bleed restriction 85 preventsthe flow of liquid to the upper end of the valve chamber as rapidly asit can be Withdrawn through the line 87, and consequently preventstransmission of the pressure existing in the lower end of the chamber i4to the upper end of the chamber 44. Means hereinafter described forautomatically controlling the cycle of operation of the inachine,incorporates means to energize the solenoid 83 when the machine isstopped and means or de-energizing the solenoid 89 when any motor of themachine is in operation. r'hus there is no idle period during which thepump is required to act against a high pressure.

It will be apparent that to cause any desired cylinder of the threecylinders l, and 3 to move in either of its two directions of movementit is only necessary to energize one of the solenoids 2l, 28, 34, 35,39, and 40. Consequently, any desired sequence of operations of thethree cylinders may be accomplished by simply energizing the solenoidsin the proper sequence.

If it is desired to have the table cylinder 3 move the workpiece intobroaching position, which is accomplished by moving the cylinder to theleft, as viewed in the drawing, solenoid 39 is energized, thusconnecting the line 4| to line Z4 and at the same time connecting line25 to the low-pressure discharge line 42. Under these conditions aportion of the huid from the pump will pass through valve 43, pipe 58containing valve 59 and pipe 6I to the line 4I, during which flow itwill pass through the adjustable throttle valve 63 in line 4|. Thethrottle valve 63 will cause a pressure drop which will result in alower pressure in line 'I9 than that existing in line TS, due to thefact that no now is occurring in pipe 36 and, consequently, there is nopressure drop through valve 52. The high pressure in line 18 will shiftthe spool of the low-pass valve to the right, thereby connecting line'i9 to line 65 and subjecting the upper end of the valve chamber 44 tothe pressure existing in the pipe 4I below the valve 63. As a result ofthese connections piston 45 with the plunger i5 will automaticallyadjust itself to by-pass to the low-pressure reservoir through line 53all of the fluid delivered by the pump except that amount which willproduce the predetermined pressure drop through valve S3 required toovercome the spring 52. Since the mechanism maintains a uniform pressuredrop through a Xed opening the rate of ow of liquid through the line 4Iwill remain constant, independent of variations in the resistance tomovement of cylinder 3. The total pressure against which the pumpdischarges under these circumstances will be the pressure required tomove the cylinder 3 at its desired speed plus the relatively smallpressure drop through valve 83. lf it is desired to adjust the speed ofmovement of the cylinder 3 it is only necessary to adjust the degree ofopening of the throttle valve 63. If the opening is reduced a smallerquantity of the liquid will pass for the given pressure drop maintainedby spring 52 and, consequently, the speed of the cylinder will bereduced and vice versa. It is apparent that the mechanism will operatein a similar manner to cause reverse or return movement of the cylinder3 when solenoid 4G is energized in place of solenoid 39.

When it is desired to effect movement of the broach-handling cylinder 2in downward direction, solenoid 35 is energized, thus connecting lines3G and I9 and at the same time connecting lines 3l and Il. The valvemechanism previously described will, under these circumstances, maintainthe speed of cylinder 2 at a uniform rate in exactly the mannerdescribed in connection with the cylinder 3, except that in this casethe pressure in line 'I8 will be lower than that in line 7S, and thelow-pass valve will assume the position illustrated in the drawings inwhich it connects the upper end of valve chamber 44 with the pipe at apoint below the adjustable restriction 62. A5 in the previous case, therate of flow through the line 36 may be adjusted by adjusting the degreeof opening of the throttle valve 62.

Return or forward movement of the cylinder' 2 is effective in the samemanner by energizing the solenoid 34 instead or" the solenoid 35.

When it is desired to cause the downward movement of the main cylinderI, solenoid 2l is energized, thus connecting pipe 30 to pipe 8 and atthe same time connecting pipe Il to pipe 3l. Under these circumstances,the liquid from the pump will pass through valve 4.3 and the adjustablethrottle valve 59 to line 3U, and thus causing a downward movement ofthe cylinder l; and the mechanism in valve housing 43 will serve tomaintain the now in pipes 58 and 30 at the uniform rate required tomaintain thek pressure drop across Valve 59 equal to the differentialpressure required to overcome spring 52. Since under these circumstancesno liquid will be flowing in lines 36 or 4I, the low pass valve 66 will,under the influence of spring 89, assume the position illustrated in thedrawings in which it connects line I8 to line 95. Thus, the upper end ofvalve chamber M will be subject to the pressure in pipe 58 beyond theadjustable throttle valve 59. As in previous instances, the quantity ofliquid supplied through the main cylinder I may be adjusted by adjustingthe degree of opening of the throttle valve 59 since for the iixedpressure dro-p maintained by the mechanism in valve 43 the quantity ofliquid which will pass valve 59 is a function of the size of the openingprovided therein.

Reverse or upward movement of the cylinder I is eiective in the sam-emanner by `energizing solenoid 28 in place of the solenoid 21.

It will be noted that successful operation of the flow control mechanismdepends upon the fact that flow occurs in only one of the lines 39, 36,and 4I at a time. This requires the presence of some means to block flowin the lines to the cylinders which are not operating at any given time,or at least so reduce flow that no appreciable pressure drop will occurthrough the throttle valves of the inoperative cylinders. In certainmachines, such as broaching machines, it is possible to prevent suchflow by moving each operating cylinder lunit against a mechanicalabutment in each direction to stop the movement and consequently theflow of liquid to the unit upon completion of its stroke even though theposition of the four-way valve leading to the cylinder does not change.In that case, it is unnecessary to employ a blocking valve in the fluidline to the cylinder. In broaching machines of the type hereindisclosed, it is a common practice to limit the stroke of the tablecylinder in both directions by positive abutments and consequently thespring centering device may be omitted from valve 33 if such anarrangement is employed without affecting the mode of operation of themachine. While the same practice may be employed with the cylinders Iand 2, it is preferred to employ a blocking valve in lines 39 and 36 tofacilitate adjustments in the stroke of the cylinders. As previouslyindicated, the four-way valves 29 and 94 perform the necessary blockingfunction when neither solenoid is energized by reason of the action ofthe spring centering device.

It will be observed that the adjustable throttle valve 59 is connectedin series with the adjustable throttle valves 62 or 63, the latter beingconnected in parallel with respect to each other. Consequently, whenliquid is supplied to either the broach-handling cylinder 2 or thetablemoving cylinder 3, it will also ow through the adjustable throttlevalve 59. In the particular embodiment of the invention illustrated anddescribed, it is assumed that the quantity of liquid required to operatethe cylinders 2 and 3 at their desired speeds is so much smaller thanthat required to operate the larger broach pulling cylinder I that theilow required to operate the cylinders 2 and 3 will cause no appreciablepressure drop on passage through valve 99. Consequently,r adjustment ofvalve 59 made for the purpose of adjusting the speed of operation of thecylinder I will not appreciably affect the speed of operation of thecylinders 2 and 3. The valves 62 and ,portion of the machine.

reciprocating plunger IOS which is depressed by i9 63 are connected inparallel because of the fact that the amount of fluid required tooperate the cylinders 2 and 3 is more nearly in the same order and,consequently, a parallel connection is desirable to enable adjustmentsof the speed of one of these two cylinders to be made without affectingthe speed of the other. It is apparent that, if desired, all three ofthe restriction valves may be connected in parallel in a manner morefully disclosed in applicants copending application, Serial No. 548,294,filed August 5, 1944. Reference may be had to that application for moredetailed description of the multiple flow control mechanism and thepreferred form of adjustable throttle valve employed therein.

The cycle of operation of the three cylinders is controlled by means ofan electrical circuit, hereinafter described in combination with aplurality of limit switches operated by the three cylinders. As bestshown in Figure l, the limit switches include a switch 96 having a pairof operating arms 9'I and 98 xed to a rotatably mounted switch contactoperating shaft 99. The contacts and internal mechanism of the switch,

being conventional, are not illustrated or described, it beingsuflicient to note only that the switch incorporates a pair of contactswhich, in one rotative position of the shaft 99, are electricallyconnected together and in another rotative position are disconnected. Asbest shown in the fragmentary side elevation of Figure 2, the arms 97and 98 are axially offset with respect to each other and are provided,respectively, with flanges |99 and IOI adapted to engage, respectively,lugs |92 and |93 which are iiXed to the broaching cylinder I. Thehousing of the switch 96 is fixed in any suitable manner to a stationaryportion of the machine in such position that the flanges IBB and IUIwill be engaged by the lugs I92 and i433. Lug I92 is displaceddownwardly from the plane of Figure 1 with respect to lug |93, with theresult that lug |93 will not engage flange i799 of the arm 91, while lugI92 will not engage flange IBI of arm 98, the latter flange beingengaged by the lug I93. The construction and arrangement of the lugs andthe limit switch 96 are such that when the ram I approaches its upperposition illustrated, lug |92 will engage the flange I9!) of arm 97 androtate the shaft 99 with its attached arms 9'I and 9B into the positionillustrated in Figure l in which position the contacts of the switch arebroken. When the ram approaches its lower position, the lug I 93 willengage the ilange I9! of arm 98 and rotate the `shaft 99counterclockwise approximately 99 to close the electrical circuitbetween the two contacts of the switch. The switch 96 and the operatingmeans therefor are indicated diagrammatically in Figure 3 in which thedouble arms 97 and 98 are represented as a single arm engagedalternately by the lugs |92 and |99 for the sake of simplicity. Theswitch is of the snapacting type so that it will be held in each of itstwo positions of adjustment. This is represented 'diagrammatically inFigure 3, by the spring pressed detent E94.

The breaching ram I is also provided with a limit switch Ill'l, which isxed to a stationary Switch I9? contains a and III.` When the plunger |99is depressed,v

contacts are electrically connected, and contacts are disconnected When,on downward movement of the ram, the cam lug |09 is withdrawn fromcontact with the plunger |08, a spring |2 forces the plunger outwardlydisconnecting contacts H0 and making an electrical connection betweenthe contacts The handling cylinder 2 is provided with a limit switch H3which is identical in construction and operation to the limit switch 96previously described and which is operated by a pair of lugs ||4 and ||5carried by the handling cylinder 2. As best shown diagrammatically inFigure 3, when the handling cylinder is up, lug ||4 operates the switchto break electrical communication between the two contacts of theswitch. When the handling cylinder reaches the bottom of its downwardstroke, the lug |5 operates the switch in the opposite direction to makean electrical connection between the contacts. The switch H3 is alsosnap acting as indicated diagrammatically by a spring-pressed detent ||6in Fig. 3.

The handling cylinder 2 is also provided with a limit switch ||8 havinga plunger ||9 adapted to be depressed by a cam lug on the handlingcylinder-when the cylinder reaches the upper end of its stroke. Theswitch ||8 is similar in construction and mode of operation to theswitch |01 previously described and contains two pairs of contacts |24and |22, as indicated diagrammatically in Figure 3.

For reasonsv which will appear more fully hereinafter, the handlingcylinder 2 is also provided with a solenoid operated latch mechanismindicated generally at |24 which serves, when the machine is idle, toprevent the handling cylinder, if it should sink by gravity, fromcompleting the last few inches of its downward stroke. The latchmechanism includes a housing containing a solenoid |25 and a latchplunger |26 adapted to engage a lug |21 on the handling cylinder tolimit downward movement of the cylinder when the plunger is in itsoutermost position illustrated in Figure l. The plunger is normally heldin its outermost position by means of a spring |28 and is retracted onenergization of the solenoid |25. The arrangement of the lug |21 is suchthat when the cylinder 2 is in its lower-most position the lug preventslatch plunger |26 from projecting outwardly under the iniluence ofspring |28.

The table cylinder 3 is provided with a pair of limit switches |30 and|3| which are identical in construction and mode of operation to limitswitch |01, except that they incorporate only one pair of contacts, asbest shown diagram,- matically in Figure 3. The limit switch |30 ismounted in such a position that when the table cylinder reaches the endof its stroke in the direction in which it moves the table intobroaching position and engages (or the table engages) a xed abutment|32, the plunger |33 of the switch |30 will be depressed by any suitablemeans xed to the cylinder or table, such as the projection |34. Suchdepression closes the circuit between th'e pair of contacts of theswitch |30, as indicated diagrammatically in Figure 3. The switch |30 isof the type which will close upon a very minute inward movement of theplunger |33 and in which the closing position can be set with greataccuracy to coincide with the point at which the cylinder or tableengages the fixed abutment. The limit switch |3| contains a simi- 12 larplunger |35 which is depressed by means of a cam lug |36 on the cylinder3 when the cylinder reaches the opposite end of its stroke, as indicateddiagrammatically in Figure 3. Both are opened by constantly actingsprings.

Figure 3 is a diagrammatic illustration of the circuit employed tocontrol the operation of the cylinders of the machine. As there shown,the circuit comprises a pair of main line conductors |40 and |4|connected to any suitable source of electrical power. The line |4| isdivided into two lines, |42 and |43, which are connected, respectively,to one contact of the two pairs of contacts in a double pole, doublethrow switch |44. When the switch |44 is in the position illustrated,line |42 is connected to line |45 and the circuit is broken between line|43 and a line |46. The electrical connection of line |45 with a line|41 is controlled by means of the normally open contact |48 of a relay|40, the coil of which is connected between the line |40 and |4| bymeans is provided with a holding circuit |54 connected in parallel withthe line |5| and containing a normally open contact of the relay |49.When the relay |49 is energized, contacts |48 and |55 close. If switch|46 is in the position illustrated, closing of contact |48 connects lineI4! with the line |41, and closing ofcontact |55 closes the parallelholding circuit |54 which maintains the energization of the relay |49until such time as the emergency stop button |52 is depressed.

The connection of line |41 with line |4| places the circuit in acondition to start the normal cycle of operation of the machine, sinceall of the control switches andy relays and the valveoperating solenoidsare connected in parallel between the lines. |40. and |41. Thus, thereare provided the following lines connected in parallel between the.lines |40 and |41; lines |60, |6|, |62, |53, |64, |65 (the latter beingdivided i into a pair of parallel lines |55a and |65b), |66,

|61, |63, |69. (the latter having a parallel branch |6Sa), |10 (thelatter being divided into a pair ci parallel lines |.10a and |1019), andline |1.|. Line |50, contains the coil of a relay |16 having threenormally Open contacts |11, |18, and |19,

and also contains a normally open starting switch button |52, and thenormally closed contact |83 of a relay |84. The coil of relay |84 isconnected in line |63. Thecontact |11 of relay |15 ,controls a relayholding circuit |05 connected in parallel across the contacts of thestarting switch |82, as a result of which, on depression o the startingbutton, the relay |16. will be energized, thus closing all of its`contacts, and the .contact |11 will maintain the relay |16 ener.-

gizedafterV thestarting buttonis released. Contact |18 of the relay |16islocated in the line IE5-a, and contact |10 is located. inthe line |61.Line |6| contains the limit switch 3| and also the coil of a relay |85,having a normally open contact |31 located, in line |10b. Line |62containsrthe limit switch |33 and also the coil of a relay |68, havingthree normally open contacts |80, |90, and |9|, and a normallyclosedvcontact |92. Contact |89 is in line |69; contact |90 is in line|10a; contact |9| is in line |1; and contact |92 is in line |68. Line|63 contains the limit switch |3 and also the coil of the aforementionedrelay |8,4. Relay |84 has two normally closed contacts, namely, contact|83 in line |69 and H93 in line l 10a, and three normally open contacts,namely, contact |94 in line |64, l95 in line 199D, and |98 in line |1|.Line |84 contains the limit switch 96 and also the coil of a relay l9`i'having two normally open contacts, namely, contact |95 in line ii and|99 in line Hilo, and two normally closed contacts, namely, contact iliin line |98, and 292 in line Ill,

Line E55 contains the solenoid 89 of the pressure control valve S3 shownin Figure l. As previously indicated, the line |95 is connected to theline lill' through the two parallel lines |6511 and S9517. Line E89contains the solenoid i9 of valve 98. Line |91 contains the solenoid 39of Valve 39 and also contains the contacts 52| of switch H9. The line|58 contains the solenoid 3d of valve 33 and also the contacts |22 ofswitch H8. Line |99 contains the solenoid 35 of valve es and also thecontacts H9 of switch |91, and the parallel branch |99@ contains thelatch solenoid i255. Line |18 contains the solenoid 28 of valve l@ andis connected to the line |41 by a pair of branch lines Illia and |1919,the former branch line containing the contacts iii of the switch |91.

The electrical circuit so far described constitutes the complete circuitnecessary to operate the broaching machine through its normal cycle. Italso serves to interlock the position of the various cylinders toprevent the operation ci any cylinder when the cooperating cylinders arein an improper position, and it further operates to automaticallycorrect any improper positioning of the cylinders, and thereafter permitautomatic resumption of the cycle of operation,

The operation of the circuit is as follows: In Figure 3, all of therelays are illustrated in the position they assume when the cylinders ofthe machine are in their starting positions and no power is suppliedtothe lines Idil and |4|. rhis will be the theoretical position assumedwhen the power supply is cut off after the inachinc has stopped at theend of its cycle of operation. Actually, as hereinafter pointed out, ifthe machine is left idle for any appreciable period of timeI one or moreof the vertically positioned cylinders may sink down by gravity andassume an improper position. While the foot valves I2 and i9 serves tohold the cylinders in their upper positions, unavoidable leakage willoften permit a gradual sinking of the cylinders during long idleperiods. The result of such occurrences will be dealt with hereinafter.

If the lines E49 and lill are energized when the parts are in theposition illustrated, no power will be supplied to the line |46 becausethe jogging switch llt is in the position it assumes when the machine isset for normal operation. Likewise, no power will be supplied to theline |41 because of the open contact |48 of relay |49. Consequently, nopower is supplied to any of the parallel lines connecting lines |49 and|551, and none of the valve solenoids will be energized.

The machine is placed in condition to be started by connecting lines |49and 4| to a suitable source of electrical power and by depressing thereset button i555, which establishes a circuit through the coil of relay|49, thus causing contacts 955 and llil of that relay to close. Contact|55 establishes a holding circuit through line 655-3 for maintenanceY ofthe energization of the relay M9 and contact |43 closes communicationfrom line Uli through branch line |42, switch |44, andline .E45 to theline |41. As the result of this operation, the opposite ends of allthe'parallel lines |99 and |1'|, inclusive, are subject/toV ai' voltagedifferential which will cause a current iiow through any parallel linewhich forms a closed path for the iiow of the electric current. Afterthe reset button is depressed to energize line lill, the only one of theparallel lines which is closed to the passage of electric current is theline |6| which contains the coil of relay |86. Consequently, as soonasthe reset button is depressed relay !88 is energized and closes itscontact |81. rihe contact |81 is in line |1011 which contains the opencontact 99, and thus the closure of contact |81 does not aifect line|191) when the parts are in the position illustrated in the drawing.Since none of the remaining parallel lines |69 and iGZ to lll,inclusive, provide a closed circuit, it is necessary to depress thestarting button |82 to start the machine.

As soon as the starting button is depressed, a circuit is establishedthrough the coil of relay |16 causing that relay to close its contacts|11, |18, and |19. The contact |11 establishes a holding circuit for therelay |16 through the branch line |85 and, consequently, the relayremains ener-l gized after the starting button is released. Contact |18,on closing, establishes a current flow through line |95a, line |85, thepressure control solenoid 89, thus establishing pressure in thehydraulic system in the manner previously described in connection withthe mechanism illustrated in Figure 1. At the same time, current flow isestablished through line |61 by reason of the closure of relay conta-ctH9. yThis energizes the solenoid 3S of the table control Valve 38, andshifts the valve to the position in which it effects inward movement ofthe table. Such movement shifts the workpiece into broaching position.

In this connection, it will be observed that injury to the broach or tothe work would result if,

' on inward movement of the table, the handling cylinder had sunk downduring a previous idle period to a point in which the lower end of thebroach was below the top of the workpiece. It is for this reason thatthe switch i8 is provided. It will be noted that, as long as thehandling cylinder is in its up-permost postion, the switch |18 will bein a position in which its upper contact closes communication betweenthe contacts |2I in line |61. If, however, the handling cylinder is notat the top of its stroke, communication between the contacts I2| will bebroken and noV current will be supplied to the solenoid 39. When thisstate of affairs exists, the switch ||8 closes communication betweencontacts |22 in line |88, thus energizing solenoid 34 of the handlingcylinder valve 33. This energization of solenoid 34 causes the valve toshift to a position in which the handling cylinder 2 is returned to itsuppermost starting position. This energization of solenoid 94 ispossible because relay |88 is de-energized and, therefore, its contact|92 is closed. As soon as the handling cylinder reaches the top of itsstroke, switch H8 returns to the position illustrated iin Figure 3, inwhich it closes the circuit through line 291 to effect theaforementioned inward movement of the worktable.

As soon as the table begins to move in, switch |3| is opened, breakingthe circuit through line |6| and de-energizing relay |86, with theresult that the previously closed contact |81 is then opened. When thetable reaches its innermost position,

switch iS is closed, establishing a circuit through tact |92. If at thistime the breaching cylinder 1S is in its uppermost position, as itshould be, switch |01 will be in the position illustrated in which itopens the connection between contacts I in line |10a, and, consequently,the closure of contact |99 will have no effect. Similarly, the closureof contact |9| will have ne effect because contact |96 in line |1| isopen. However, the closure of contact |89 closes the circuit throughline |69 to energize solenoid 35 of valve 33, thus causing the handlingcylinder to move downwardly. At the same time, the parallel branch line|69a is energized, thus causing retraction of the latch |26.

In this connection, it will be noted that it is undesirable to have thehandling cylinder move downwardly unless the breaching cylinder is inits uppermost position, since otherwise the automatic chuck on thebreaching cylinder will not be open to receive the breach when it isreleased by the handling chuck, and in the subsequent step in the cyclethe breaching cylinder will move downwardly without the breach. This inturn would result in breaking the breach when the table moved outwardlyat the end of the downward movement of the breaching cylinder. It is forthis reason that the switch |01 is provided. It will be noted that ifthe breaching cylinder is not at the top of its stroke, the switch willbe in its lowermost position, in which it breaks the circuit betweencontacts H in line |69 and thus prevents energization of the solenoid35. At the same time, the switch |01 connects contacts of line |10a(thus completing the circuit through line Illia and the solenoid 28,which in turn shifts the main valve 25 i-nto a position in which itreturns the breaching cylinder to the top of its stroke. As soon as thecylinder reaches the top of its stroke, switch |01 returns to theposition illustrated in Figure 3, thus permitting energization ofsolenoid 35 and downward movement of the breach-handling cylinder.

Since the switch |30 is of the type which can be very accuratelyadjusted to close only when the werktable is in its extreme innermostposition against abutment |32, ne downward movement of thebreach-handling cylinder` can occur unless the table is in its fullinwardposition because as soon as it leaves that position, switch |30deenergizes solenoid |88 and opens contact |89 in line |69. This insuresthat the workpiece will be in the proper position te receive thebreaching tool.

During the downward stroke of the breachhandling cylinder, the switch H8shifts downwardly from the position shown in Figure 3, breaking thecircuit through line |61 and connesting contacts |22 of line |68. Nocurrent will flow through line |68 at this time, due to the fact thatthe table is in, and consequently relay |88 is energized, thus openingcontact |92.

When the handling cylinder reaches the end of its downward stroke,switch H3 is closed by lug H5 on the cylinder, thus energizing relay|88. Enger-ization of relay |86 closes contacts |99, |95, and |98, andopens contacts |93 and |83. The closing of contact |96 has no effectbecause line |64 is open at switch 96. The closing of contact |95completes a circuit through the branch |651) of the pressure controlsolenoid line |65. The opening of contact |93 does not aiect the circuitthrough line |a because that circuit is already opened by the switch|01. The opening of contact |83 breaks the circuit through the startingbutton line |60, thus de-energizing relay |16 anf` opening its contacts|11, |18, and |19. The open'- ing of contact |18 dos not interrupt thecurrent through the pressure control solenoid 89 because of thesimultaneous closing of Contact |95, which closes the circuit throughthe branch line |6512, thus maintaining the pressure control solenoidenergized. The opening of contact |11 breaks the holding circuit forrelay |16. The opening of contact |19 has ne effect because line |61 isopen at contacts |2|. However, the closing of contact |96 completes thecircuit through line |1| and energizes solenoid 21 of the main valve 26,thus shifting the valve to a position in which it causes downwardmovement of the breaching cylinder to eiect the breaching stroke of themachine. During this state in the cycle of operation, line |66 is openat contact |98; line |61 is open at contact |19 and contacts |2| line|68 is open at contact |92; line |69 is open at contacts ||0 as seen asthe breaching cylinder starts down; line |10a is open at contact |93;and line |101) is open at contacts |81 and |99. As a result of theseconditions, none of the other cylinders of the machine can move duringthe breaching stroke.

When the breaching cylinder reaches the end of its downward breachingstroke, lug |03 closes switch 96, thus energizing relay |91 (contact |94having previously closed). This opens contacts 20| and 202 and closescontacts |98 and |99. At this point, line |61 is open at contacts |19and |2|; line |68 is open at contacts |92 and 20|; lines |69 and |69aare open at contact I0; line |10a is open at contact |93; line |101) isopen at contact |81; and line |1| is open at Contact 202. Line |66,however, is then closed, thus energizing solenoid 40 ef valve 38 andshifting the valve to a position in which it causes an outward movementof the worktable. It will be observed that such outward movement occursafter the breaching cylinder has reached the end of its downward stroke.As soon as the table leaves its innermost position, switch |30 isopened, de-energizing relay |88, thus opening contacts |89, |96, and|9i, and closing contact |92. The opening of contacts |89, |90, and |9|does not aiect` the lines in which they are located because at thisstage in the cycle 'i those lines are opened at contacts ||0, |93, and

202, respectively. Closing of contact |92 does not aiect line |68because that line is open at contact 29|. When the table reaches the endof its outward stroke, switch |3| is closed, thus energizing relay |86and closing its contact |81. The closing of Contact |81 closes thecircuit through line |1012 and line |10, thus energizing solenoid 28 ofvalve 26 and shifting that valve inte the position in which it causesupward or return movement of the breaching cylinder. During the returnmovement of the breaching cylinder, switch 96 is held in its closedposition by the detent |86. This insures that the relay |91 will remainenergized and that, therefore, the table cannot move in or the breachhandling cylinder up. When the breaching cylinder reaches the upper endof its stroke, switch |01 is shifted into the position illustrated inthe drawing, and switch 98 is opened by lug |02. This shift of themicroswitch |91 opens the circuit between contacts of line |1011, whichline is already open at contacts and |93, and connects contacts |I0 inline |69 which is already open at contact |89. The opening of switch 96de-energizes relay |91, thus breaking contacts |98 and |99 and closingcontacts 20| and 202. The opening of contact |98 de-energizes solenoid40. The opening of contact |99 completes the de-energization of thesolenoid 28 and thus relieves the breaching cylinder of operatingpressure. The closing of contact 202 has no eiect on line |1| becausethat line is open at contact |9|. However, the closing of contact 20|completes the circuit through line |68 and energizes solenoid 34 ofvalve 33, thus shifting the valve to a position in which it effectsupward movement of the broach handling cylinder 2. As soon as thecylinder 2 leaves its lower position, latch |26 is projected by spring|28 because line 69a is broken at contact |89.

During upward movement of the broach-handling cylinder, switch ||3 isheld closed by the detent ||6, but when the handling cylinder reachesthe end of its upward stroke, switch ||3 is opened by lug I 4, thusde-energizing relay |84. This opens contacts |94, |95, and |96, andcloses contacts |83 and |93. In addition, when the handling cylinderreaches the upper end of its stroke, the switch |8 shifts to theposition illustrated in the drawings, in which it closes communicationbetween contacts |2| and breaks the connection between contacts |22.These changes complete the cycle of operation and bring the machine to astop, inasmuch as line |66 is open at contact |98; line |6'| is open atcontact |19; line |68 is open at contact |22; lines |69 and |69a areopen at contact |89; line l10n is open at contacts |90 and line |1017 isopen at contact |99; and line |1| is open at contacts |9| and |96. Itwill be noted also that the pressure on the machine is relieved byreason of the breaking of both branches |65a and |65b of the pressurecontrol line |65.

It will be observed that throughout the cycle described above, the latchsolenoid |25 was retracted only when the handling cylinder was caused tomove down. At all other times, including the stop position, the latchsolenoid is deenergized and the latch advances under the influence ofspring |28 into retaining position. The object of the latch |26 is toprevent the handling cylinder from moving downwardly under the influenceof gravity during idle periods to such a point that the automatic broachhandling chuck secured to the broach handling cylinder will release thebroach. In this connection, it will be understood that the latch is sopositioned as to stop the cylinder just before the chuck releasemechanism contacts the release abutment.

The latch also prevents the handling cylinder from falling by gravityduring idle periods suciently far to insert the broach, if carried bythe handling cylinder chuck, into the chuck carried by the broachingcylinder l or to prevent the broach, if carried by the broachingcylinder chuck, from being projected into the broachhandling chuck. Itfurther prevents downward movement of the cylinder during idle periodfrom closing switch I3 since such closure would result in injury to thebroach if the machine was started following an emergency stop after theworktable moves in, if, during the idle period, the handling cylindersank all the way to the end of its stroke and the broaching cylinderalso sank all or part way down.

It will be understood that in accordance with the conventional practicethe downward stroke 01 the broach-handling cylinder,`the inward strokeof the work iixture cylinder, and the upward stroke of the broachcylinder are limited by fixed abutments in all cases, with the resultthat it is immaterial whether the operating pressure is maintained afterthe cylinders reach the positive abutment. The length of the upwardstroke of the broach-handling cylinder may be readily adlOf `adjustments are desirable in order to adjust the stroke of the twocylinders to correspond to the length of the broach employed.

If, after the machine is automatically stopped in the above describedmanner at the end of the broaching cycle, the broach handling cylindershould sink down by gravity, the switch |8 will shift to its lowerposition, thus closing the circuit through line |59 and energizing thesolenoid 34 of valve 33 to shift that valve to a position in which itreturns the broach-handling cylinder to its uppermost position as soonas the machine is restarted. The worktable cannot move in until thehandling cylinder returns to its uppermost position and shifts theswitch ||8 to the position illustrated in Figure 3. As a result there isno possibility, on restarting the machine, that the work moving tablewill collide with the broach.

It will be noted that if, during the idle period following an automaticstop at the end of a cycle,

ity, switch |01 will be shifted downwardly closing the circuit betweencontacts and opening the circuit between contacts ||0. These changes dof not have any immediate effect because line |69 is already open atcontact |89, and line |10a is already open at contact |96. However,when, during the subsequent cycle, the table moves inwardly tobroachingI position, it will close switch |30, thereby energizing relay|88 and closing contacts |89, |90, and |9|. Consequently, line |10a willbe energizedand line |69 will be disconnected at contacts I0, with theresult that the broaching cylinder will return to its upper position andthe handling cylinder will not move down. As soon as the broachingcylinder reaches its upper position, the switch |01 is returned to theposition illustrated, and the cycle is resumed by downward movement ofthe handling cylinder.

To restart the machine following an automatic stop, it is only necessaryto depress the starting button |82, thus energizing relay |16 toinitiate a repetition of the previously described cycle of 0peration.

At anytime during a cycle of operation, the machine can be stopped bydepressing the emergency stop button |52. This de-energizes relay |49and opens contacts |48 and |55, thereby disconnecting line |41 from thesource of electrical energy. To reinstate the machine in condition tooperate following an emergency stop, it is necessary to depress thecycle reset button |53, which re-energizes relay |49 and returns thecontacts |48 and |55 to a position in which line |41 is connected to theelectrical source. If the machine were stopped during a portion of thecycle subsequent to the end of the downward movement of the broachhandling cylinder, the cycle will resume a depression of the resetbutton 53. If the machine was stopped at an earlier portion of thecycle, it is necessary to depress rst the reset button |53 and then thestarting button |82 to restart the machine. If, during the interveningidle period, the positions of the remaining switches and relays remainedunchanged the machine, on restarting, will resume its cycle where itleft off. Z

It will be appreciated that by reason of the possibility of stopping themachine at any point during its 'cycle by the emergency stop button andby reason of the possible sinking by gravity of the cylinders I and 2during idle periods, the three moving cylinders may assume a widevariety of relative positions when the machine is restarted. The controlcircuit provided in accordance with the present invention automaticallyprevents any movement of any of the-three cylinders which will result ininjury to the broach, work iixture, or machine when the machine isrestarted, regardless of the relative positions of the three cylindersat the time of starting. A few possible relative positions of thecylinders and the means by which they were cured during the cycle havebeen described above. However, many other relative positions arepossible. For example, if the machine is stopped while the worktable ispart way in during the beginning of the cycle and thereafter thebroach-handling cylinder, which is then carrying the breach, sinks downby gravity before the machine is restarted, then, on restarting, thehandling cylinder will return to its upper position and the movement ofthe worktable will not be resumed until after the work handling cylinderreaches its upper position. This result is achieved by reason of thefact that downward movement of the broachhandling cylinder shifts theswitch ||8 downwardly, thus breaking the circuit through line |61 andclosing the circuit through line |68. As soon as the handling cylinderis fully returned, switch I l 8 returns to the position illustrated andinward movement of the table resumes.

Another possibility is that the machine may be left idle following anautomatic stop at the end of the cycle and that during the idle periodthe breaching cylinder will sink to the extreme lower end of its stroke,thus closing switch 9B. However, closure of switch 96 cannot energizerelay |91 because relay |84 is de-energized thereby breaking the circuitof relay |91 at contact |94. Relay |84 is energized only when thehandling cylinder is at the lower end of its stroke and the latchprevents the handling cylinder` from reaching that position during idleperiods. Therefore, under the conditions stated, when the machine isstarted, the handling cylinder will move up if it is not at the top ofits stroke and then the table will move in. At the end of the inwardtable stroke, the handling cylinder cannot move down because contacts|||J are open; but the circuit through line lilla is closed and,therefore, the breaching cylinder is returned to its upper position.From that point, the normal cycle resumes with a downward movement ofthe handling cylinder.

If the machine is stopped during the breaching stroke, it will, onrestarting, resume the broaching stroke where it left off, since thereis no possibility of a change of position of the work handling cylinderor table under those circumstances during the idle period. The samething is true if the machine is stopped during the return movement ofthe breaching ram; that is to say, on restarting under thesecircumstances, the upward movement of the ram will resume.

A complete tabulation of all improper positions which may result, andthe way they are automatically corrected before the normal cycleresumes, is given below. Each improper position assumed prior torestarting is indicated in the lefthand column, while in the right-handcolumn are listed the various cylinder movements which occurautomatically in the order given when the machine is restarted andbefore the normal cycle is automatically resumed.

Improper Positions Corrective Movements A. Table Out 1. Machine stoppedat end of cycle a, Handling cylinder sinks l. Handling cylinder returnsb. Breach cylinder sinks pnrl. Table moves in tially or fully 2.Branching cylinder returns c. Handling cylinder sinks 1. Handlingcylinder returns and breaching cylinder 2. Table moves in sinkspartially or fully 3. Broaching cylinder returns 2.Machinestoppedduringbroach return by breaching cylinder a. Brcachingcylinder sinks None required-cycle rc partially or fully sumes 3.Machinestoppedduringbroach return by handling cylinder a. Handlingcylinder sinks None required-cycle resumes b. Broachng cylinder sinks 1.Handling cylinder returns partially 2. Machine stops 3. On restarting,table moves 1n 4. Brouching cylinder returns c. Broaching cylindersinks 1. Broaching cylinder refully turns B. TableV Intermediate Strokel. Machine stopped during inward movement of table a. Handling cylindersinks l. Handling cylinder returns b. Broaching cylinder sinks l. Tablemoves in fully or partially 2. Broachingcylinder returns c. Handlingcylinder sinks and 1. Handling cylinder returns breaching cylinder sinks2. Table moves in fully or partially 3. Branchingcylinderrcturns 2.Machine stopped during out- None required-cycle reward movement of tablesumes C. Table In 1. Machine stopped before handling cylinder moves downa. Handling cylinder sinks None required-cycle resumes b. Broachingcylinder sinks l. Broaching cylinder repartially or fully turns c.Handling cylindersinksond 1. Broaching cylinder rcbroaching cylindersinks turns partially or fully 2. Machine stopped during down- Same asfor corresponding 2. ward movement of handling positions under C-lcylinder 3. Machine stoppedduringbroach- None required-cycle reingstroke sumes It will be observed from the above table that the automaticcorrective movements take place in such an order that no damage canoccur to the broach, the workpiece, or the machine, and that everypossible position that can result during operation or after an emergencystop at any point in the cycle is taken care of. In each case, thecorrective movements listed leave the cylinders in a relative positionthey should assume during some point in the normal cycle. From thatpoint on, the cycle resumes normally. It may be noted that no mention ismade of the possibility of the handling cylinder sinking fully. This isdue to the fact that a full sinking movement is prevented by the latch.

It should be noted that all of these functions are achieved by a verysimple arrangement of parallel circuits, in which every single valvesolenoid and relay operating coil is connected directly across the fullline voltage. This basic arrangement insures that the full operatingvoltage is available to actuate each solenoid or coil at all times andgreatly facilitates modification and adaption of the circuit todifferent types of machines.

The remaining portions of the circuit so far not mentioned, which arelargely located in the lower lefthand portion of Figure 3, have noutility except for use in jogging the various cylinders during tool andxture set-up. It is highly desii-able in a machine of this type toprovide manually controlled means for moving each cylinder in anydesired direction to any desired extent, as such movements are requiredto facilitate attachment and adjustment of the tools and work holdingfixtures during machine set-up opera- 21 tions. Accordingly, there isprovided an auxiliary set of manual controls for use in such cases.

The jogging control circuit employs as its source of current the mainconductor |40 and the branch |45 of the main conductor |4|. When it isdesired to operate the manual jogging controls, the previously mentionedswitch |44 is shifted to break the connection between the lines |42 andi 45 and to complete an electrical connection between the lines |43 and|45, thus energizing the latter.

In order to control movement of the table in either direction, a pair ofmanually operated push-button switches 204 and 205 are provided. Each ofthese switches has flve contacts, those of the switch 254 beingindicated by the letters a, b, c, d, and e, and those for the switch 205being indicated f, g, h, lc, and m. The contactor of switch 204 isspring-biased to a position in which it connects contacts a and b. Whendepressed it connects contacts c, d, and e. The contactor of switch 205similarly connects contacts f and g in its normal position and connectscontacts h, lc, and m, when depressed. Contacts c and m are connected toline |46; contacts d and f are connected together; contacts b and h areconnected together; contacts e and lc are connected by lines 2 I0, 2|and 2 I2 to line |65 at a point to the right of the pressure controlsolenoid 89; contact a is connected by a line 2 I4 to line |61 betweensolenoid 39 and the contact |10; and contact g is connected by a line 2|5 to line |66 between solenoid 40 and contact |98.

As the result of this arrangement, all of the circuits connected toswitches 204 and 205 are normally open. However, when only switch 204 isdepressed solenoid 40 is energized through line |46; contacts c, d, f,and g, and line 2|5, and the pressure control solenoid 39 is energizedthrough line |46, contacts c and e and lines 2||| and 2|2. Thusdepression of switch 204 causes the work table to move out, and suchmovement continues only so long as the switch 204 is depressed.Likewise, the pressure control solenoid is energized only so long as theswitch 204 is depressed, with the result that no pressure exists in thesystem except when the switch is depressed. This enables the operator toleave the pump running during the set-up operations without heating theoil and yet enables him to shift the table outwardly to any desiredextent by the touch of the switch button. Switch 205, when depressedalone, operates in the same manner to energize solenoids 80 and 39 tobuild up pressure and effect an inward movement of the worktable.

If both of the switch buttons 204 and 205 are depressed simultaneously,no movement of the worktable results, but the pressure control solenoidis energized to subject the system to operating pressure.

A pair of manually operated switches 2|8 and 2 I9 are provided forsimilarly energizing the solenoids and 21 respectively of the ramcontrol valve 26 to effect any desired upward or downward movement ofthe ram. These switches, being identical in construction and mode ofoperation to switches 204 and 205, need no furthe description.

A third pair of manually operated switches 220 and 22| are provided forenergizing the solenoids 34 and 35 respectively of the handling cylindercontrol valve 33. These switches are likewise similar in constructionand operation to the switches 204 and 205. It will be noted, however,that on depression of switch 22| both the solenoid 35 and the latchsolenoid |25 are energized-,1' whereas on depression of the switches204, 205, 2|8, 2|9, and 220 the solenoids 40, 39, 28, 2l, and 24 areenergized, respectively, without energizing the solenoid |25 to releasethe latch. Thus the latch normally operates to limit downward movementof the handling cylinder during setup operations. The only exception iswhen switch button 22| is depressed to cause downward movement of thehandling cylinder.

It is apparent, therefore, that the hereinbefore described controlcircuit not only achieves an automatic positively interlocked andfool-proof control of maximum simplicity, but lends itself readily to anexceedingly simple and practical jogging control for use in tool set-upoperations.

Preferably the jogging control buttons will be made inaccessible to theordinary operator since they need be employed only by skilled machineset-up men. It is possible by manipulation of the jogging buttons tocause damage, but, as previously pointed out, it is impossible by anymanipulation of the normal controls, namely, the starting button, theemergency stop button, and the cycle reset button, to cause any injuryto the broach, work, or machine.

What is claimed is:

l. In a hydraulic shuttle pull-broaching machine, a double-actingpositive displacement motor for operating a movable worktable between aretracted and a broaching position, a doubleacting positive displacementmotor for operating a broach-handling slide between a retracted and anadvanced position, a double-acting positive displacement motor foroperating a broaching ram through a broaching and a broach-returnstroke, a separate four-way reversing valve for controlling admission ofoperating liquid to each motor, separate means for shifting each fourwayvalve, each said means including a pairof solenoids, energization of oneof which causes a shift of the valve in one direction and energizationof the other causes a shift in the opposte direction, and automaticmeans controlled by the position of the motors for energizing saidsolenoids one at a time in sequence to produce a complete cycle ofoperations including an ad- Vance of the table to broaching position, anadvance of the broach-handling slide, a broaching stroke of the ram, aretraction of the table, a broach-return stroke of the ram, and aretraction of the broach-handling slide, said lastnamed means includingautomatic means operable to return the broach-handling slide to itsfully-returned position before any advance of the table, automatic meansto return the ram to fully-returned position before any advance of thebroach-handling slide, automaticv means to prevent advance movement ofthe broach-handling cylinder if the table is not fully advanced andautomatic means to prevent a broaching stroke of the ram if the table isnot fully advanced.

2. In a hydraulic shuttle pull-broaching machine, a double-actingpositive displacement motor for operating a movable work table between aretracted and a broaching position, a doubleacting positive displacementmotor for operating a breach-handling slide between a retracted and anadvanced position, a double-acting positive displacement motor foroperating a broaching ram through a broaching and a broach-returnstroke, a separate four-Way reversing valve for controlling admission ofoperating liquid to each, motor, separate means for shifting each.four-- 23 way valve, each said means including a pair of solenoids,energization of one of which causes a shift of the valve in onedirection and energiaation of the other causes a shift in the oppositedirection, and automatic means controlled by the position of the motorsfor energizing said solenoids one at a time in sequence to produce acomplete cycle of operations including an advance of the table tobreaching position, an advance of the broach-handling slide, a breachingstroke of the ram, a retraction of the table, a breach-return stroke ofthe ram and a retraction of the broach-handlingT slide, means forrendering said automatic means inoperative, and manually controlledmeans efrective when said automatic means is rendered inoperative forselectively energizing any one of said solenoids.

3. In a hydraulic shuttle pull-breaching machinea double-acting positivedisplacement motor for operating a movable worktable between a retractedanda breaching position, a doubleacting positive displacement motor foroperating a breach-handling slide between a retracted and an advancedposition, a double-acting positive displacement motor for operating abreaching ram through a broaching and a breach-return stroke, a constantdisplacement pump, branch conduits for conducting liquid from the pumpto both sides of each motor, a separate four- Way reversing valve foreach motor associated with said branch conduits, automatic means forshifting said four-way valves one at a time in either direction toproduce a complete cycle of operations including an advance oi the tableto breaching position, an advance oi the broachhandling slide, abroaching stroke of the ram, a retraction of the table, a broach-returnstroke of the ram and a retraction of the breach-handling slide, aby-pass valve for ley-passing to low pressure a portion of the liquiddischarged by the pump, and means for automatically controlling thedegree of opening of said by-pass valve to maintain the rate oi flow ofliquid to each motor as that motor operates at a constant value which isdifferent for each motor and which is independent of the resistanceencountered by each motor, said last means including means in theconduits from the by-pass valve to said motors for imposing a diierentresistance to the flow to each motor, and means responsive to thepressure drop in each conduit as flow occurs therein for controlling thedegree oi opening of said by-pass valve.

e. In a hydraulic shuttle pull-broaching machine, a double-actingpositive displacement motor for operating a movable worktable between aretracted and a broaching position, a doubleacting positive displacementmotor for operating a broach-handling slide between a retracted and anadvanced position, a double-acting positive displacement motor foroperating a breaching ram through a broaching and a broach-returnstroke, a constant displacement pump, branch conduits for conductingliquid from the pump to both sides of each motor, a separate four-wayreversing valve for each motor associated with said branch conduits,automatic means for shifting said four-way valves one at a time ineither direction to produce a complete cycle of operations including anadvance of the table to broaching position, an advance of thebroach-handling slide, a broaching stroke of the ram, a retraction ofthe table, a broach-return stroke of the ram and a retraction of thebroach-handling slide, a by-pass valve for by-passing to low pressure vaCgl lil

portion of the liquid discharged by the pump, and means forautomatically controlling the degree of opening of said by-pass valve tomaintain the rate of flow of liquid to each motor as that motor operatesat a constant value which is different for each motor and which isindependent of the resistance encountered by each motor, said last meansincluding means in the conduits from the by-pass valve to said motor formposing a different resistance to the flow to each motor and meansresponsive to the pressure drop in each conduit as iiow occurs thereinfor controlling the degree of opening or said by-pass valve, and meansfor independently adjusting the resistance to flow to each motor.

5. In a hydraulic broaching machine, a doubleacting positivedisplacement motor for operating a movable .vorktable between aretracted and a broaching position, a double-acting positivedisplacement motor for operating a broaching ram through a broaching anda broach-return stroke, a constant displacement pumpy branch conduitsfor conducting liquid from the pump to both sides of each motor, aseparate four-Way reversing valve for each motor associated with saidbranch conduits, automatic means for shifting said four- Way valves oneat a time in either direction to prod ce a complete cycle of operationsincluding an advance of the table top breaching position, a broachingstroke of the ram, a retraction of the table, and a broach-return strokeof the ram, a by-pass valve for ley-passing to low pressure a portionci' the liquid discharged by the pump, and means for automaticallycontrolling the degree of opening oi said by-pass valve to maintain therate of flow of liquid to eacn motor as that motor operates at aconstant value Which is diiierent for each motor and which isindependent of the resistance encountered by each motor, said last meansincluding means in the conduits from the by-pass valve to said motorsfor imposing a diierent resistance to the flow to each motor and meansresponsive to the pressure drop in each conduit as low occurs thereinfor controlling the degree of opening of said by-pass valve, and meansfor independently adjusting the resistance to ilcw to each motor.

6. In a vertical shuttle-type pull down broaching machine having ahydraulic motor for moving a Work xture into and out of breachingposition, a hydraulic motor for moving a broachhandling chuck toward andaway from a broachpulling chuck, a hydraulic motor for moving abroach-pulling chuck toward and away from the broach-handling chuck, thecombination of control means for automatically operating said unitsthrough a normal shuttle breaching cycle, said control means including,means operable automatically at any time during the cycle before thefixture is fully advanced to return the broachhandling motor to fullyretracted position if it is not fully retracted and to prevent inwardmovement of the Work fixture motor unit the broachhandling motor isfully retracted, means operable automatically at any time during thecycle before the breach-handling motor is fully advanced to restore thebreach-pulling motor to its fully advanced position if it is not fullyadvanced, and means operable during operation of said last mentionedmeans to prevent advance movement of the broach-handling cylinder untilthe broachpulling cylinder is fully advanced.

7. In a vertical shuttle-type pull down broaching machine having ahydraulic motor for mov- 75 ing a work xture into and out of breachingposition, a hydraulic motor for moving a breachhandling chuck toward andaway from a breachpulling chuck, a hydraulic motor for moving abreach-pulling chuck toward and away from the breach-handling chuck, thecombination of control means for automatically operating said unitsthrough a normal shuttle breaching cycle, said control means including;means operable automatically at any time during the cycle before theiixture is fully advanced to return the breachhandling motor to fullyretracted position if it is not fully retracted and to prevent inwardmovement of the work nxture motor until the breach-handling motor isfully retracted, means operable automatically at any time during thecycle before the breach-handling motor is fully advanced te restore thebreach-pulling motor to its fully advanced position if it is not fullyadvanced and to prevent advance movement of the breach-handling cylinderuntil the breachpulling cylinder is fully advanced; means to preventretraction of the work xture motor after it has fully advanced unlessthe breach-handling motor is in its fully advanced position and thebreach-pulling motor has previously been fully retracted during thecycle, means to prevent advance movement of the breach-pulling motorafter it has completed the breaching stroke until after the work fixturemotor is fully retracted, and means to limit advance movement of thebroachhandling motor when the machine is idle.

8. In a vertical shuttle-type pull down breaching machine having ahydraulic motor for moving a work fixture into and out of breachingposition, a hydraulic motor for moving a breachhandling chuck downwardlytoward and upwardly away from a breach-pulling chuck, a hydraulic motorfor moving a breach-pulling chuck upwardly toward and downwardly awayfrom the breach-handling chuck, the combination of control means forautomatically operating said units through a normal shuttle breachingcycle, said control means including: means operable automatically at anytime during the cycle before the fixture is fully advanced to return thebreachhandling motor upwardly to fully retracted position if it is notfully retracted and to prevent inward movement of the work xture motoruntil the breach-handling motor is fully retracted, means operableautomatically at any time during the cycle before the breach-handlingmotor is fully advanced downwardly to restore the breach-pulling motorto its fully advanced upward position if it is not fully advanced, andmeans operable during operation of said last mentioned means to preventadvance downward movement of the breach-handling cylinder until thebreach-pulling cylinder is fully advanced upwardly.

9. In a vertical shuttle-type pull down breaching machine having ahydraulic motor for moving a werk fixture into and out of breachingposition, a hydraulic motor for moving a breachhandling chuck downwardlytoward and upwardly away from a breach-pulling chuck, a hydraulic motorfor moving a breach-pulling chuck upwardly toward and downwardly awayfrom the breach-handling chuck, the combination of control means forautomatically operating said units through a normal shuttle breachingcycle, said control means including means operable automatically at anytime during the cycle before the fixture is fully advanced to return thebreachhandling motor upwardly to fully retracted position if it is notfully retracted and to prevent inward movement of the work xture motoruntil the breach-handling motor is fully retracted, means operableautomatically at any time during the cycle before the breach-handlingmotor is fully advanced downwardly to restore the breach-pulling motorto its fully advanced upward positie-n if it is not fully advanced andto prevent advance downward movement of the breach-handling cylinderuntil the breach-pulling cylinder is fully advanced upwardly, means toprevent retraction of the work fixture motor after it has fullyradvanced unless the breachhandling motor is in its fully advanced dewnward position and the breach-pulling motor has previously been fullyretracted downwardly during the cycle, means to prevent upward advancemovement ofthe breach-pulling motor after it has completed the breachingstroke until after the work fixture motor is fully retracted, and meansto limit downward advance movement of the breach-handling motor when themachine is idle.

10. In combination, a plurality of positive displacement double-actinghydraulic motors each having a movable element, a separate four-wayreversing valve for controlling admission of operating liquid to eachmotor, separate means for shifting each four-way valve, each said meansincluding a pair of solenoids, energization of one of which eects ashift of the valve in one direction and energization of the other ofwhich effects shift of the valve in the other direction, automatic meanscontrolled by the position of the movable elements of said motors forenergizing said solenoid one at a time in a predetermined sequence tocause said motor elements to perform a cycle of operations, saidlast-named means including a switch mechanism operated by one of saidmotors when said motor is away from the position it should occupy when asecond motor which operates immediately prior thereto in said sequenceis so operating, said switch mechanism having contacts in the circuit ofthe solenoid which on energization elfect return of said one motor tesaid position and having contacts in the circuit of the solenoid whicheffect said prior operation of the second motor, said rstmentionedcontacts being closed and the secondmentioned contacts being opened whensaid switch mechanism is so operated by said one meter.

BENEDIC'I WELTE.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 2,186,379 Harrington Jan. 9, 19402,194,568 Romaine Mar. 26, 1940 2,209,608 Nye July 30, 1940 2,239,237Lapointe Apr. 22, 1941 2,254,708 Nye Sept. 2, 1941 2,256,332 Welte Sept.16, 1941 2,274,191 Davis Feb. 24, 1942 2,307,228 Monroe Jan. 5, 19432,317,099 Groene Apr. 20, 1943 2,374,243 Somes Apr. 24, 1945 2,395,702Welte Feb. 26, 1946 2,429,938 Mansfield Oct. 28, 1947 2,446,397 WeiteAug. 3, 1948

